---
title: "List a one-time send's A/B test groups"
method: GET
path: "/v1/newsletters/{newsletter_id}/test_groups"
tags: ["Newsletter Variants"]
---

# List a one-time send's A/B test groups

`GET /v1/newsletters/{newsletter_id}/test_groups`

## Request

- Base URL: `https://api.customer.io`
- URL: `https://api.customer.io/v1/newsletters/{newsletter_id}/test_groups`
- Auth: HTTP bearer

Returns information about each test group in a one-time send (referred to as a "newsletter" in our APIs), including content ids for each group.

## Response `200`

Returns metadata for each test group in a one-time send.

- object
  - `test_groups` object[]: Each object represents one of the test groups.
    - `id` integer: The ID of the A/B test group.
    - `name` string: The name of the A/B test group.
    - `label` string: The name of the variant.
    - `winner` boolean: Whether this variant is the winner of the test.
    - `content_ids` string[]: A list of content_ids for each variant in the test group.

## Other responses

- `404`: The one-time send or variant does not exist.
- `429`: Your request is over the 10-per-second limit. `Retry-After` tells you how many seconds you must wait before you send the next request.

## Changes

- **2026-09-02** `5da2740beeb5`: 1 info
  - added the media type `application/json` for the response with the status `429`

[Operation history](https://skmtc.dev/customer/apis/customer-io-journeys-api-reference/changes/v1/newsletters/:newsletter_id/test_groups/get.md)

---

[API](https://skmtc.dev/customer/apis/customer-io-journeys-api-reference.md) - [All operations](https://skmtc.dev/customer/apis/customer-io-journeys-api-reference/llms.txt) - [OpenAPI document](https://skmtc.dev/customer/apis/customer-io-journeys-api-reference/revisions/ac0b282053fe?raw)